The present invention relates to an axle system for a two-wheeled vehicle and in particular for a bicycle operated by muscular energy at least in part. The bicycle may be provided with an auxiliary motor drive configured in particular as an electric motor to assist the rider if and as desired. Use is likewise conceivable with other bi- and multicycles.
Various axle systems with a quick release mechanism have become known in the prior art to allow fast and easy mounting and demounting of bicycle wheels.
In many of the quick releases for bicycles as known in the prior art the clamping force is applied by flipping an eccentric member after adapting the clamping length by means of a tightening nut and a stopper. The drawback of this system is that first the clamping length must be set by means of the tightening nut before the clamping length and the clamping force can be checked by flipping the eccentric member. As a rule a number of cycles is required until the proper clamping length and thus the clamping force are suitable.
Due to safety requirements for quick releases the dropouts of modern bicycles tend to be configured not smooth but comprising end bearings for the axle system so as to initially ensure continued safe accommodation of the axle system at the dropouts even after releasing the clamping force. Because of these end bearings or lugs at the dropouts the opened distance must be enlarged wherein the stroke length of a classic quick release lever obtained by flipping the eccentric member is not always sufficient to release the clamping force and to overcome the additionally required lift for overcoming the additional end bearings. Therefore many systems require to operate not only the quick release lever but also to turn the screw nut on the opposite side in the opening direction for removing the wheel every time that a wheel is released and later clamped. Thus the axle system must be adjusted with every wheel change.
In EP 1 801 005 B1 a quick release in particular for bicycles has become known offering greater ease of operation. In this quick release the clamping force is not applied by flipping an eccentric member but via a screwed connection. A spring mechanism allows to pull the operating lever axially outwardly out of engagement and to freely turn it back in to quickly tighten the quick release. The known system operates reliably and allows precise adjustment of the clamping force required. Moreover the operating lever may be rotated to any desired direction after setting the clamping force.
Due to safety requirements and the increased opened distance which may be for example 5 mm, the quick release lever must be rotated approximately 5 or 6 turns every time that a wheel is released and later clamped, before the wheel can be removed or is again reliably clamped.